District voters ousted Michael A. Brown from the D.C. Council on Tuesday after a string of revelations about his personal and political finances hobbled his campaign and came to embody residents’ concerns about the ethics of city leaders.

With all the precincts reporting, challenger David Grosso (I) edged past Brown (I) by about 18,000 votes for one of two citywide at-large seats reserved for a non-Democrat.

Grosso’s victory could reshape the balance of power on the 13-member council, empowering newer residents who have been flexing their clout in District elections. Grosso, who made his opponent’s character a chief issue in the race, joins a council that has been trying to move beyond a turbulent year that saw two council members resign in disgrace.

Grosso declared victory shortly before midnight and in an interview, he praised the effort that brought him into office.

“I am really excited,” said Grosso, 42, a lawyer from Brookland. “The residents of the District of Columbia are ready to bring a new day to D.C. politics, and I am really proud of all the work that everyone put in to make this a reality.”

In an interview early Wednesday, Brown faulted himself for his loss to Grosso. “I don’t know if he defeated me as much as I defeated myself with my personal problems,” Brown said, adding that he was proud of his legislative record.

Grosso prevailed on a day that saw District residents swarm to the polls, causing some to wait in line for more than two hours before they cast a ballot.

For the second at-large seat, Vincent B. Orange (D) won his bid for reelection with 37 percent of the vote. But Orange’s winning margin fell short of past Democratic nominees for council, a sign his future political ambitions for higher office could be stalled.

In other races, Del. Eleanor Holmes Norton easily won reelection to a 12th term as the city’s non-voting member of Congress. In contested ward council races, Marion Barry (D-Ward 8) sailed past an independent challenger in his bid for a third term on the council while incumbent Yvette Alexander (D-Ward 7) beat Republican Ronald Moten. Incumbents Jack Evans (D-Ward 2) and Muriel Bowser (D-Ward 4) were running unopposed.

Council Chairman Phil Mendelson (D), appointed to replace Kwame R. Brown who resigned before pleading guilty to federal bank fraud and a minor campaign violation, easily prevailed in a special election to retain the seat.

But Brown’s defeat highlights an electorate who showed up to the polls dissatisfied with incumbents after the turmoil of the last year in the D.C. government. Months before Brown stepped down, Harry Thomas Jr. resigned from his Ward 5 seat after pleading guilty earlier this year to stealing money meant for youth programs. Three associates of Mayor Vincent C. Gray (D) also pleaded guilty this year in the ongoing investigation into his 2010 campaign.

The son of the late Commerce secretary Ronald H. Brown and once a rising star in District politics, Brown, 47, was never implicated in any criminal probes into the District government or politicians. But he was battered by a series of a news reports about his failure to pay his bills and taxes on time. Recently, his campaign was dealt a major setback when he reported that $113,000 was stolen from his campaign account.

Brown blamed his former treasurer, accusing the ex-aide of making unauthorized payments to himself. But with no charges filed in the matter, the controversy appeared to fuel public concerns about Brown’s stewardship of his finances. Brown’s campaign was dealt another setback after The Washington Post reported in September that his driver’s license had been suspended five times in the past eight years.

Edmund C. Fleet, a nonprofit executive who lives in Hillcrest, said he voted for Grosso and Cooper. “I definitely feel like we need change on the council,” he said. “It was just hard to vote for any incumbent.”

“If Michael Brown can’t handle his own personal finances, how can he handle the finances of the city?” asked Fleet, 43. “We want people of integrity.”

After unsuccessful Democratic bids for mayor in 2006 and the Ward 4 council seat in 2007, Brown switched his party affiliation to independent to compete for the at-large seat in 2008. He closely linked himself to his father during the campaign and easily overpowered two GOP incumbents in a year in which President Obama drove tens of thousands of voters to the polls.

On the council, Brown developed a reputation as an affable, progressive lawmaker, teaming with some colleagues to champion funding for social services. In the first half of his term, Brown was widely viewed as a possible future candidate for mayor or council chairman. His citywide ambitions began to dim after he pushed through a controversial proposal in 2010 to legalize Internet gambling, which was repealed this year amid criticism it was approved without a public hearing.

According to election returns, Grosso racked up sizable margins over Brown in many predominantly white neighborhoods west of the Anacostia River. Brown performed well in communities east of the Anacostia but fell short of his 2008 margins in several majority-black neighborhoods.

Former D.C. Council member Bill Lightfoot said Brown lost despite his high name recognition because he developed a reputation as “ethically challenged.”

“With your name, you have to be branded as something,” said Lightfoot, who supported Grosso. “We knew his name, but the brand had high negatives for being ethically challenged.”

Grosso is a former aide to council member Sharon Ambrose, who represented Ward 6 from 1997 to 2oo7. When she retired, Grosso worked for Norton before being tapped to head up CareFirst’s government affairs office.

Tim Craig is The Post’s bureau chief in Pakistan. He has also covered conflicts in Iraq, Afghanistan and within the District of Columbia government.

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